Sensors for robotic devices

ABSTRACT

A robotic device having a body having an upper surface resiliently connected to a lower surface and having a bump sensor including a contact point on the lower surface which contact point is in its normal position centrally located within a sensor device being an aperture having a conducting inner periphery which sensor device is located in the upper surface such that a bump on the upper surface is detected by the robotic device when the contact point abuts the aperture periphery. The robotic device also includes a drop sensor for use in association with a lower surface of a robotic device said lower surface having a periphery around which a plurality of such drop sensors are located, each drop sensor including a body having moveably located therein a vertically oriented member such that when any such member becomes positioned over a drop in terrain the vertically oriented member will drop down and trigger the production of a signal which is sensed by the robotic device.

TECHNICAL AREA

[0001] This invention relates to sensor devices for robotic andautonomous machines and, in particular, to sensors for determiningobstacles and hazards in both the horizontal and vertical.

BACKGROUND TO THE INVENTION

[0002] Robotic machines may be used for a number of purposes but forassistance and easy description of the invention we will consider themachine being used in association with a self mobile vacuum cleaner.

[0003] Such machines have a means to cause them to operate in variousdirections and have a computer system associated therewith whereby themachine can remember which parts of a room it has cleaned and also it isnecessary for the machine to be able to note when it strikes anobstruction, partly to be able to move away from the obstruction at thetime but also so as to avoid the obstruction in the future whilst stillcleaning the remainder of the floor.

[0004] The types of obstructions can be both solid obstructions on thefloor, such as pieces of furniture, walls or incursions into the room ofsuch things as benches or the like and can also be “negative”obstructions such as a stair or step down which the machine will fall ifnot stopped.

[0005] As far as the positive instructions are concerned there havepreviously been proposed various forms of bump sensors or objectdetection sensors for a robotic device however these are usually of aremote sensing type, which are usually IR or RF sensors, and which tendto be associated with complicating the electronics of the device and canbe quite expensive.

OUTLINE OF THE INVENTION

[0006] It is a first object of the invention to provide in a roboticdevice, bump sensors which are simple in construction but reliable androbust in use which can control the necessary movement of the deviceand, at the same time, provide a required signal to enable the memory ofthe device to navigate it as required.

[0007] A second object of the invention is to provide a robot devicehaving sensors which can identify when the surface upon the robot ismoving changes to prevent the robot, for example, falling down stairsand which, again, can give a good indication for future reference toavoid the problem again.

[0008] The invention in a first aspect is a robotic device having a bodyhaving an upper surface resiliently connected to a lower surface andhaving a bump sensor including a contact point on the lower surfacewhich contact point is centrally located in its normal position within asensor device being an aperture having a conducting inner peripherywhich sensor device is located in the upper surface such that a bump onthe upper surface is detected by the robotic device when the contactpoint abuts the aperture periphery.

[0009] It is preferred that the robotic device detect a bump by means ofan electrical signal generated when the contact point touches the sensordevice. It is further preferred that the conducting inner periphery ofthe sensor device consist of a multiplicity of contact points, or switchsegments, so that a computer device within the robotic device, saiddevice having a memory, can determine the location of the bump on therobotic device.

[0010] While an electrical contact is the preferment here it isenvisaged other signals such as infrared and pneumatic could be used.

[0011] It is also preferred that the upper surface be a plate devicewhich rests on a plurality of ball transfers affixed to a plate devicecomprising the lower surface. By this means the upper plate is free tomove relatively to the lower plate by a distance equal to the differencein radius of the upper and lower plate. It is therefore preferred thatthe upper plate have a greater diameter than the lower plate.

[0012] It is further preferred that the upper and lower surfaces each belocated within housings such that the entire unit comprises the body ofthe robotic device. It is also preferred that the upper plate be rigidlyconnected to its housing while the lower plate is attached to a drivemechanism which includes a locomotion means such as wheels.

[0013] The invention in a second aspect is a drop sensor for use inassociation with a lower surface of a robotic device, said lower surfacehaving a periphery around which a plurality of such drop sensors arelocated, each drop sensor including a body having moveably locatedtherein a vertically oriented member such that when any such memberbecomes positioned over a drop in terrain the vertically oriented memberwill drop down and trigger the production of a signal which is sensed bythe robotic device.

[0014] It is preferred that the signal is an interruption to the passageof light between at least one LED and receptor. The signal used howevermay be of any kind which is considered appropriate alternatively anyswitching system desired could be used.

[0015] It is preferred that the signal cause the robotic device tochange direction away from the drop.

[0016] It is also preferred that the vertically oriented members used inthe drop sensors take the form of rods. It is further preferred thatthese rods be able to resume their original positions within the dropsensors once the robotic device has returned to substantially levelterrain.

[0017] The rods may preferably comprise armatures of solenoids and onoperation of the solenoid the rods are caused to be raised. While thismethod is preferred it is envisaged that any retraction method,including pneumatic means may be used.

[0018] In order that the invention may be more readily understood weshall describe by way of non limiting embodiment a robotic device whichincorporates both aspects of the invention therein with reference to theaccompanying drawings.

BRIEF OUTLINE OF THE DRAWING FIGURES

[0019]FIG. 1 Shows a schematic drawing of the interior of a roboticdevice;

[0020]FIG. 2 Shows an upper view of the interior of a robotic device;

[0021]FIGS. 3,4 and 5 Show the components of the bump sensor of theinvention;

[0022]FIG. 6 Shows a cross-section through the components of the bumpsensor;

[0023]FIG. 7 Shows the drop sensor of the invention in its loweredstate;

[0024]FIG. 8 Shows the drop sensor in the raised position;

[0025]FIG. 1 shows the interior of a robotically controlled cleaningdevice 10 having an upper surface or plate 11, in which the bump sensor20 is shown (FIG. 2),. Drop sensors 30 are shown arranged around thelower periphery of the lower surface or plate 12.

[0026] In its complete form the cleaning device has a body whichincludes a chassis and drive wheels.

[0027] The robotic device has an outer shell rigidly attached to theupper plate 11. The upper plate rests on multiple transfer balls thatare affixed to the lower plate 12 and these plates are able to moverelative to one another whilst supported by these transfer balls. Theupper plate has a greater diameter than the lower plate and is able tomove relatively to by a distance equal to the difference between theradii of the two plates when the robotic device is bumped.

[0028] There are also provided spring means which keep the upper platecentred over the lower plate when no contact is made between an objectand the outer shell of the robotic device.

[0029] The bump sensor 20 which detects any bump activity includes acontact member 21 mounted fixedly on lower plate 12 and extendingthrough aperture 23 in upper plate 11. The periphery of this aperture issurrounded by conducting segments 22 each of which is identifiable by acomputer device associated with the robotic device.

[0030] The arrangement is such that movement of the upper plate 11caused by the robotic device hitting some object causes the contactmember 21 to hit one of the conducting segments 22 and a signal to begenerated which the robotic device's computer recognises and permits thelocation of the bump to be identified

[0031] Subsequent to encountering an impediment to movement the actualmovement of the device can be controlled by software however variousmodes of movement can be used.

[0032] If required, the software associated with the device can map theposition of an obstacle in memory.

[0033] It will be seen that the device can if required move in a more orless random appearing manner throughout the room and, if associated witha vacuum cleaner, the vacuum cleaner will effectively clean the room asit passes over an area.

[0034] The walls of the room would provide an obstruction and if a wallis struck effectively head on then after the machine is reversedsomewhat and again commences to move this movement will tend to beparallel to the wall.

[0035] In another arrangement the robotic device can strike a wall,rotate through 90°, move along the wall a distance half its diameter,turn again through 90° and proceed back across a floor therebysystematically cleaning it if the robotic device is a cleaning robot.

[0036] Clearly any range of movement can be programmed into such adevice, it is unique however in terms of the use of the bump sensor. Itcan be seen that the bump sensor of the device is basically simple, wefind it quite satisfactory to use only four (4) segments but if it wasrequired a greater number than this, preferably eight (8) but possiblysix (6) could be used, the more sensors which are used the more delicatethe manoeuvring can be to cover the area as quickly as possible.

[0037] In the second aspect of the invention we provide drop sensors 30as shown in FIGS. 7 and 8 to ensure that the device does not “fall” downstairs or, say a step in the middle of a split level room.

[0038] There may be four (4) such sensors, although if required therecould be more, and these each comprise a rod member 32 mounted forvertical movement within a body 33 of the device which rod members mayhave a rounded lower end or preferably a ball 36 of a relatively lowfriction material, such as nylon attached to their lower ends. In theembodiment of the invention shown the lower part of the rod member,adjacent ball 36, consists of a tightly wound coil 37 to lendflexibility to this part of the drop sensor.

[0039] The rods themselves are preferably of iron or steel and passupwardly through the windings of solenoid.

[0040] Also are two pairs 34 of LED's and two phototransistors 35 thearrangement being such that when the robotic device is moving over eventerrain and the rod member 32 is in its elevated position (FIG. 8) afirst LED/receptor pair is occluded while light transfer is continuousacross a second pair. Should the drop sensor pass over a stair or otherchange in terrain the rod member falls to the position shown in FIG. 7and the second LED/receptor pair becomes occluded while the first opens.It is not pertinent which pair is which however this approach provides asimple means of determining when a drop has been reached as a signal issent to the device's computer.

[0041] When the computer receives the signal it can stop the robot andthe solenoid becomes energised and causes the rod member 32 to beretracted thereby passing the LED/receptor pairs to be returned to theiroriginal state. The robotic device meanwhile will know that it is freeto move away from the step.

[0042] Once the movement of the device is stopped, the solenoid isenergised so that the rod and the ball are raised to no longer extendbelow the level of the device, the drive motors are commenced to causethe device to move at 180° to its initial movement until the device willhave cleared the edge of the step, the solenoids can then be releasedand the rod or rod members dropped into contact with the surface, thedrive wheels are manipulated to turn the device through a pre-determinedangle and then it commences to move along that line.

[0043] If, say, this movement is not such as to cause it to move awayfrom the step or the like then it is possible that one of the rods onthe side of the device will pass over the edge, the operation isrepeated, the forward movement is stopped, the rod is raised byoperation of the solenoid, the device moves rearwardly by a distancesufficient to ensure that it has cleared the step, it is caused torotate through a pre-determined angle, the solenoid can be released sothat the rod comes into contact with the ground and forward movement isagain effected.

[0044] Again, should this be required, the operating computer of thesystem can note where the rod dropped over the edge so as to avoidcontact with the edge during further movement.

[0045] It will be seen that the sensors provided in this way arebasically very simple, the solenoid permits the sensor to be removedfrom any likelihood of contact with the edge of the obstruction and themovement of the device is relatively rapidly reestablished and thecleaning, assuming it be a vacuum cleaner, continued.

[0046] Whilst in this specification we have described two aspects of theinvention it will be appreciated that they both effect the samefunction, although under different circumstances.

[0047] The bump sensors operate when the shell of the device contacts anobstruction, the segmented switch is caused to move relative to the mainchassis of the device, electrical contact is made and once this occurs,the remainder of the operation occurs automatically.

[0048] The stair sensitive rods cause effectively an identical operationif they drop downwardly, as when they pass over the edge of a step, theonly difference being the additional step of causing the rod members torise by use of a solenoid so that they clear a drop before the roboticdevice moves.

[0049] Whilst simple sensors for providing information concerningvarious obstacles to a robotic device have been described herein it isenvisaged that these could be distributed around the machine as desiredand that any modification in their mechanical arrangement will notdepart from the scope of the invention.

The claims defining the invention are as follows:
 1. A robotic devicehaving a body having an upper surface resiliently connected to a lowersurface and having a bump sensor including a contact point on the lowersurface which contact point is in its normal position centrally locatedwithin a sensor device being an aperture having a conducting innerperiphery which sensor device is located in the upper surface such thata bump on the upper surface is detected by the robotic device when thecontact point abuts the aperture periphery.
 2. A robotic device asclaimed in claim 1 wherein the robotic device detects a bump by means ofan electrical signal generated when the contact point touches the sensordevice.
 3. A robotic device as claimed in claim 2 wherein the conductinginner periphery of the sensor device consists of a multiplicity ofcontact points, or switch segments, so that a computer device having amemory, and which computer is located within the robotic device, candetermine the location of a bump on the robotic device.
 4. A roboticdevice as claimed in claim 3 wherein the upper surface can moverelatively to the lower surface.
 5. A robotic device as claimed in claim4 wherein the upper surface is a plate device which rests on a pluralityof ball transfers affixed to a plate device comprising the lowersurface.
 6. A robotic device as claimed in claim 5 wherein the upperplate can move relatively to the lower plate by a distance equal to anydifference in radius of the upper and lower plate.
 7. A robotic deviceas claimed in any of claims 1 to 6 wherein at least the upper surfacesis rigidly located within a housing said housing having a greaterdiameter than the lower surface.
 8. A robotic device as claimed in anyone of claims 1 to 7 wherein the lower plate is attached to a drivemechanism which includes a locomotion means.
 9. A robotic device havinga drop sensor for use in association with a lower surface of a roboticdevice said lower surface having a periphery around which a plurality ofsuch drop sensors are located, each drop sensor including a body havingmoveably located therein a vertically oriented member such that when anysuch member becomes positioned over a drop in terrain the verticallyoriented member will drop down and trigger the production of a signalwhich is sensed by the robotic device.
 10. A robotic device as claimedin claim 9 wherein the signal is an interruption to the passage of lightbetween at least one LED and receptor.
 11. A robotic device as claimedin claim 9 or claim 10 wherein the vertically oriented members used inthe drop sensors take the form of rod members.
 12. A robotic device asclaimed in claim 11 wherein the rod member can resume its originalposition within the drop sensor and signal the robotic device to returnto substantially level terrain.
 13. A robotic device as claimed in claim12 wherein the return of the rod member is effected by means of asolenoid.
 14. A robotic device as claimed in claim 13 wherein the returnof the rod member is effected by pneumatic means.